A recent development in video display systems is the use of spatial light modulators (SLMs) instead of raster-scan electronic beam devices. An SLM consists of an array of electronically addressable pixel elements. Each element either emits or reflects light to be projected on a display screen. For many applications, an SLM is binary in the sense that each pixel element may have either of two states. The element may be off and deliver no light or the element may be on and deliver light at a maximum intensity. Recent developments in SLM technology greatly impact the parallel development of high quality video display systems.
An SLM frequently used in display systems is the digital mirror device (DMD), in which each pixel element is a tiny mirror capable of individual mechanical movement in response to an electrical input. Each pixel element of a DMD reflects and modulates incident light in direction, phase, or amplitude. Recent advances in the fabrication and use of SLMs, and DMDs in particular, permit a high pixel density suitable for operation in high quality video display systems.
Standard television systems receive and display "interlaced" video data. This means that each frame of video data displayed on the standard system contains two or more fields. In a two field format, the first field may, for example, include the odd rows of the video frame. The second field may include the even rows of the same video frame. The interlaced fields making up the single frame are received and displayed successively on a standard raster-scan system and appear to a viewer as a single frame.
SLMs are capable of addressing all pixel elements of each video frame simultaneously, rather than scanning them. Various techniques for exploiting this capability to provide high quality images are being developed.